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The Mapper - Doing One Thing at a Time

A mapper is a user configurable object which knows how to graphically display one type of information in certain way. Taken alone, one single mapper will only be able to provide a very limited graphic display. As we shall see later on, the strength of the mappers does not lie in their stand-alone use, but in combining them to generate complex and flexible displays.

As each type of mapper is implemented individually, there is conceptually no limit to the number of different mappers nor the type of task they can perform. However, all mappers must adhere to the same rules when it comes to interfacing with the network plane.

A mapper consists of the following components, of which some are mandatory and some optional:

A set of parameters which defines all user configurable aspects of the mapper. One of these parameters always contains a set of flags, some of them being generic (defined in the same way for all mappers) and some may be specific for the given mapper type. The parameters normally include at least one stylus which is used to define the display properties of the output generated by this mapper. In addition to simple numerical values, such as text size, link offset or attribute scale, the parameters often also include network element selectors and expressions.
A network plane painting routine which can be called by the network plane whenever a part of the network plane must be displayed.
A mapper control dialog which allows the user to interactively configure the mapper's parameters, or at least the more important ones. The visual appearance of the mapper control dialog is standardized and parameters of the same type always use the same standardized input fields.
A bounding box specifying the rectangle on the network plane which this mapper will provide display output for.
An optional input event handler which, if available and enabled, causes the mapper to take over mouse and keyboard, allowing the user to interact with the mapper directly on the network plane. Mappers providing this feature are called input mappers.
An optional legend provider which sends legend information to the legend window.
An optional tip provider which will display context sensitive tips (also known as ``balloon messages'') when the mouse rests on an object displayed by this mapper on the network plane view.
An optional set of active network elements. This set of elements is usually defined by the mapper's selector(s). If available and enabled, this feature allows other mappers to identify the active network elements via special flag attributes (is*Active), and, e.g., to use this information in their own selector.

Besides the above components, a mapper is free to access other, usually external resources. In particular, mappers may access external files, e.g. to read in objects to be displayed on the network plane, such as annotations, bit-mapped images or polygons.

Each mapper provides the following generic flags to enable or disable the corresponding services provided by the network plane:

Flag: Enables/disables the following feature:

Control Visibility of mapper control dialog

Screen Mapper displays information on network plane view on screen

Printer Mapper displays information on printed output

Magnifier Mapper display is visible on magnifier

Legend Legend information is written into the legend window

Input Mapper takes over mouse and keyboard events when it becomes active

Bounding Box Mapper's bounding box is used to compute the full view bounding box of the network plane

Active Selection Mapper's active elements will be made accessible to other mappers

Since the output of each mapper can be controlled individually to enable or disable graphic output to screen, printer and magnifier, it is possible to design plot configurations which appear differently on the different output devices. This has some interesting applications:

Certain graphic items, such as e.g. a colored background, which are nice to see on the screen, but have negative effects when being printed (bad readability, increased consumption of ink or toner) may be disabled specifically for the printouts.
Certain small displayed items (e.g. tiny texts), which are readable only on the printer and the magnifier (since these provide a higher resolution) may be disabled on the normal screen display.
The magnifier feature is not limited to display the same information simply bigger, but may also be used to display additional information or even to instantaneously display a completely different view of the same objects.

An active input mapper, which receives the mouse and keyboard events occurring on the network plane, is visually distinguished by a different background color of the mapper control dialog. This color is user configurable. In the examples shown further down, a light green background is used for input mappers, instead of the default gray background for non-input mappers.

As this paper is not meant as a reference manual, there is no point going into the details of each of the mapper types currently available in Enif. Also, the currently implemented mappers are essentially limited to output-only mappers. There are a few network editing mappers which are still in their very early experimental phase and not of any practical use yet.

Thus, we shall limit the presentation of specific mapper types to simply illustrate some of them by means of depicting an example of their configuration in the control dialog and a small stripe of the network plane output generated using this configuration:

Figure: Mapper: Description:

Fig.6 Background Paints the background either in a constant color or using a tiled bit-mapped image.

Fig.7 Grid Generates a coordinate grid using a specified grid distance.

Fig.8 Image Displays a bit-mapped image file at a certain position scaled to a certain size. Many different graphic file formats (such as JPEG, PNG, TIFF, ...) are supported. The example shows a scanned image of a city map.

Fig.9 Annotation One or several EMME/2 annotation files are displayed.

Fig.10 Node Box Draws node boxes of a specified size and optionally writes the node numbers or node labels into them.

Fig.11 Node Value Evaluates one or several node values and represents them as a proportionally sized symbol and/or a text string. The example shows initial boardings and final alightings at transit stops.

Fig.12 Node Polygon Reads a file containing polygons and displays them. An indexed stylus can be used to color them according to arbitrary node characteristics. Optional node values can be evaluated and displayed either at the corresponding node positions or at the center of gravity of the polygons.

Fig.13 Link Base Draw link bases consisting of an arbitrary combination of a link bar, an I-node circle and a J-node circle.

Fig.14 Link Value Evaluates a link value and displays it numerically and/or as a proportional bar.

Fig.15 Transit Line Displays transit line itineraries and optionally annotates them with segment and/or stop values.

Fig.16 Segment Value Evaluates transit segment values, aggregates them to link values and displays these on the links as numeric values and/or as a proportional link bar.

Fig.17 Intersection Draws intersections and displays turn values as proportional width turns.

Fig.18 Shortest Path Computes shortest paths from or to one or several root nodes and displays the corresponding trees.

Fig.19 Diagram Several mappers are available to compute and display scattergrams and histograms for the various network element types. The example shown contains a link histogram with the distribution of vehicle miles by link speed.

**Figure 6:** Background Mapper
$\includegraphics[width=\textwidth, keepaspectratio]{cwbackground.ps}$ $\includegraphics[width=\textwidth, keepaspectratio]{npbackground.ps}$

**Figure 7:** Grid Mapper
$\includegraphics[width=\textwidth, keepaspectratio]{cwgrid.ps}$ $\includegraphics[width=\textwidth, keepaspectratio]{npgrid.ps}$

**Figure 8:** Image Mapper
$\includegraphics[width=\textwidth, keepaspectratio]{cwimage.ps}$ $\includegraphics[width=\textwidth, keepaspectratio]{npimage.ps}$

**Figure 9:** Annotation Mapper
$\includegraphics[width=\textwidth, keepaspectratio]{cwannotation.ps}$ $\includegraphics[width=\textwidth, keepaspectratio]{npannotation.ps}$

**Figure 10:** Node Box Mapper
$\includegraphics[width=\textwidth, keepaspectratio]{cwnodebox.ps}$ $\includegraphics[width=\textwidth, keepaspectratio]{npnodebox.ps}$

**Figure 11:** Node Value Mapper
$\includegraphics[width=\textwidth, keepaspectratio]{cwnodevalue.ps}$ $\includegraphics[width=\textwidth, keepaspectratio]{npnodevalue.ps}$

**Figure 12:** Node Polygon Mapper
$\includegraphics[width=\textwidth, keepaspectratio]{cwnodepolygon.ps}$ $\includegraphics[width=\textwidth, keepaspectratio]{npnodepolygon.ps}$

**Figure 13:** Link Base Mapper
$\includegraphics[width=\textwidth, keepaspectratio]{cwlinkbase.ps}$ $\includegraphics[width=\textwidth, keepaspectratio]{nplinkbase.ps}$

**Figure 14:** Link Value Mapper
$\includegraphics[width=\textwidth, keepaspectratio]{cwlinkvalue.ps}$ $\includegraphics[width=\textwidth, keepaspectratio]{nplinkvalue.ps}$

**Figure 15:** Transit Line Mapper
$\includegraphics[width=\textwidth, keepaspectratio]{cwtransitline.ps}$ $\includegraphics[width=\textwidth, keepaspectratio]{nptransitline.ps}$

**Figure 16:** Transit Segment Value Mapper
$\includegraphics[width=\textwidth, keepaspectratio]{cwsegmentvalue.ps}$ $\includegraphics[width=\textwidth, keepaspectratio]{npsegmentvalue.ps}$

**Figure 17:** Intersection Mapper
$\includegraphics[width=\textwidth, keepaspectratio]{cwintersection.ps}$ $\includegraphics[width=\textwidth, keepaspectratio]{npintersection.ps}$

**Figure 18:** Shortest Path Mapper
$\includegraphics[width=\textwidth, keepaspectratio]{cwshortestpath.ps}$ $\includegraphics[width=\textwidth, keepaspectratio]{npshortestpath.ps}$

**Figure 19:** Diagram Mapper
$\includegraphics[width=\textwidth, keepaspectratio]{cwdiagram.ps}$ $\includegraphics[width=\textwidth, keepaspectratio]{npdiagram.ps}$

Note that the above list of mapper types is by no means complete. It just shows those mappers which have already reached a stage of development which is close to production level. Some additional mappers are already under development now and we have already many more ideas for new mappers to be developed in the future.

Previous: Parameters and Configurable Objects Next: Combining Mappers to Obtain Plots

Enif - Toward a New Interface for EMME/2, Heinz Spiess, October 2000

Flag:	Enables/disables the following feature:
Control	Visibility of mapper control dialog
Screen	Mapper displays information on network plane view on screen
Printer	Mapper displays information on printed output
Magnifier	Mapper display is visible on magnifier
Legend	Legend information is written into the legend window
Input	Mapper takes over mouse and keyboard events when it becomes active
Bounding Box	Mapper's bounding box is used to compute the full view bounding box of the network plane
Active Selection	Mapper's active elements will be made accessible to other mappers

Figure:	Mapper:	Description:
Fig.6	Background	Paints the background either in a constant color or using a tiled bit-mapped image.
Fig.7	Grid	Generates a coordinate grid using a specified grid distance.
Fig.8	Image	Displays a bit-mapped image file at a certain position scaled to a certain size. Many different graphic file formats (such as JPEG, PNG, TIFF, ...) are supported. The example shows a scanned image of a city map.
Fig.9	Annotation	One or several EMME/2 annotation files are displayed.
Fig.10	Node Box	Draws node boxes of a specified size and optionally writes the node numbers or node labels into them.
Fig.11	Node Value	Evaluates one or several node values and represents them as a proportionally sized symbol and/or a text string. The example shows initial boardings and final alightings at transit stops.
Fig.12	Node Polygon	Reads a file containing polygons and displays them. An indexed stylus can be used to color them according to arbitrary node characteristics. Optional node values can be evaluated and displayed either at the corresponding node positions or at the center of gravity of the polygons.
Fig.13	Link Base	Draw link bases consisting of an arbitrary combination of a link bar, an I-node circle and a J-node circle.
Fig.14	Link Value	Evaluates a link value and displays it numerically and/or as a proportional bar.
Fig.15	Transit Line	Displays transit line itineraries and optionally annotates them with segment and/or stop values.
Fig.16	Segment Value	Evaluates transit segment values, aggregates them to link values and displays these on the links as numeric values and/or as a proportional link bar.
Fig.17	Intersection	Draws intersections and displays turn values as proportional width turns.
Fig.18	Shortest Path	Computes shortest paths from or to one or several root nodes and displays the corresponding trees.
Fig.19	Diagram	Several mappers are available to compute and display scattergrams and histograms for the various network element types. The example shown contains a link histogram with the distribution of vehicle miles by link speed.